SECONDARY BATTERIES – LEAD– ACID SYSTEMS | Bipolar Batteries

Abstract

In bipolar lead–acid battery (LAB) designs, the stack of alternate positive and negative plates with interleaved separators is replaced by a stack of conductive plates that are pasted with positive active material on one side and negative active material on the other side. The positive material on one side of this ‘bipolar plate’ faces the negative material of the neighboring plate, again with a separator between them. This unit then constitutes one 2 V cell. Such cells can be stacked together to increase the voltage of the bipolar battery. The surface area of the substrate together with the volume of the active material determines the capacity of the battery. Bipolar construction shortens the current path between the positive and negative terminals of adjacent cells in the battery. This reduces the battery’s internal resistance to current flow and improves power delivery. Additionally, bipolar construction creates a uniform current distribution and load potential over the surface of the electrodes, which provides more efficient utilization of active materials. The resultant bipolar batteries have a higher specific power (W kg−1) and power density (W L−1) than equivalent monopolar batteries and long cycle life with high-energy turnover. Bipolar batteries can be accommodated in current recycling streams for LABs and are cost-effective as lead is less expensive than the metals used in other battery chemistries.